In a study conducted at The Clever Dog Lab Vienna by researchers from the Messerli Research Institute, the Guesser–Knower task setup was put to the test. The aim of the study was to replicate the results of a study from 2014 and to test whether dogs could infer two informants’ knowledge from observing their gazes alone. The study was published online in March 2017 in Animal Cognition.

One of the issues that has been studied and a contentious issue in comparative cognitive research is whether non-human animals can take on the perspective of another individual. Humans have an ability called Theory of Mind that allows them to infer the mental state of others and understand where they are coming from.

One aspect of understanding what another person knows is understanding what others can see from their perspective, especially if it deviates from your own perspective. The researchers argue that this ability to understand what other people can see from their perspective “requires the observer to appreciate the difference between their own and another’s line of sight.” The ability to do that is called geometrical gaze following.

In order to test whether dogs could understand something about a human’s perspective, the study used three Guesser–Knower tasks. These tasks involve a “Knower,” who can point to the correct container where food is hidden, and a “Guesser,” who can only guess where the food is and could be pointing at the wrong container. However, the dog cannot watch the Knower hiding the food. Instead, the possible food containers were blocked by a screen as the Knower hid the food. The dog could only watch the gaze of the people to determine whether they knew where the hidden food would be.

The three Guesser–Knower situations were set up as Guesser Present, Guesser Absent, and Guesser Looking Away. In the Guesser Present task, the Guesser would watch as the Knower hid food in two of the containers. After the screen was lifted, each person would point to one of the containers where food was hidden. In the Guesser Absent task, the Guesser would leave the room while the Knower hid food in one container. Then, the Knower would point to the correct container and the Guesser would point to an incorrect container.

In the Guesser Looking Away task, the situation created for the purposes of this study, researchers introduced a third person. This third person would hide the food in a container. Both the Guesser and Knower looked down at a 45-degree angle, either to the right or left. Because the person hiding the food was in between the Guesser and Knower, the Knower would be able to see where the food was placed and the Guesser wouldn’t. In previous research, similar tests had been done, but where the Knower looked at the hiding place and the Guesser looked up at the ceiling. Researchers wanted the Guesser and Knower doing the same behavior to see if dogs could interpret that only one of them could see the location of the food.

In all three tasks, after the screen was raised and the Guesser and Knower pointed to a container, the dog was allowed to move forward and choose one of the containers. A total of 16 privately owned dogs participated.

On the group level, dogs selected where the Knower pointed at a rate significantly greater than chance for the Guesser Absent (with a mean of 72.3%) and Guesser Looking Away (with a mean of 61.7%) tasks and a majority of the time for the Guesser Present task (a mean of 56.2%). Individual analysis was done to determine if certain dogs preferred the Knower or Guesser, and by excluding three dogs with significant preference, the group performance remained significant.

Researchers noted that the Guesser Looking Away task provide evidence that “dogs discriminate between two possible informants on the basis of subtle perceptual cues, their lines of sight. The dogs tracked the informants’ gaze direction geometrically, thereby appreciating the difference between their own and the informant’s line of sight.”

These results suggest that the dogs can infer what others can or cannot see and make the leap to what that person then does or does not know.